/**
 * Copyright 2009-2017 the original author or authors.
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.zyplayer.doc.db.framework.db.parser;

import org.apache.ibatis.parsing.TokenHandler;

/**
 * 参数预处理类
 *
 * @author Clinton Begin
 * @author 暮光：城中城
 * @since 2019-10-10
 */
public class GenericTokenParser {
	
	private final String openToken;
	private final String closeToken;
	private final TokenHandler handler;
	
	public GenericTokenParser(String openToken, String closeToken, TokenHandler handler) {
		this.openToken = openToken;
		this.closeToken = closeToken;
		this.handler = handler;
	}
	
	public String parse(String text) {
		if (text == null || text.isEmpty()) {
			return "";
		}
		int start = text.indexOf(openToken, 0);
		if (start == -1) {
			return text;
		}
		char[] src = text.toCharArray();
		int offset = 0;
		final StringBuilder builder = new StringBuilder();
		StringBuilder expression = null;
		while (start > -1) {
			if (start > 0 && src[start - 1] == '\\') {
				builder.append(src, offset, start - offset - 1).append(openToken);
				offset = start + openToken.length();
			} else {
				if (expression == null) {
					expression = new StringBuilder();
				} else {
					expression.setLength(0);
				}
				builder.append(src, offset, start - offset);
				offset = start + openToken.length();
				int end = text.indexOf(closeToken, offset);
				while (end > -1) {
					if (end > offset && src[end - 1] == '\\') {
						expression.append(src, offset, end - offset - 1).append(closeToken);
						offset = end + closeToken.length();
						end = text.indexOf(closeToken, offset);
					} else {
						expression.append(src, offset, end - offset);
						offset = end + closeToken.length();
						break;
					}
				}
				if (end == -1) {
					builder.append(src, start, src.length - start);
					offset = src.length;
				} else {
					builder.append(handler.handleToken(expression.toString()));
					offset = end + closeToken.length();
				}
			}
			start = text.indexOf(openToken, offset);
		}
		if (offset < src.length) {
			builder.append(src, offset, src.length - offset);
		}
		return builder.toString();
	}
}
